In general, in the air conditioners, there are split type air conditioners each having an indoor unit and an outdoor unit respectively installed in a room space and an outdoor separately, and unit type air conditioners each having an indoor unit and an outdoor unit fabricated as one unit, for installation on a window or wall, wherein the split type air conditioners are used widely because, not only of sizes of the indoor units and the outdoor units that become the larger as cooling/heating capacities of the air conditioners become the larger, but also of heavy vibration of the outdoor units coming from compressors therein.
The split type air conditioner is provided with the indoor unit in a room to make heat exchange between low temperature, and low pressure gaseous refrigerant and air for supplying warm or cold air into a space to be air conditioned, the outdoor unit in an outdoor to compress, condense, and expand the refrigerant for making the heat exchange at the indoor unit, and refrigerant pipelines between the indoor unit and the outdoor unit.
The indoor unit is provided with an indoor case having an inlet and an outlet for drawing/discharging room air, an evaporator in the indoor case for making heat exchange between the low temperature, and low pressure gaseous refrigerant passing therethrough and air, and an indoor fan and a motor on one side of the evaporator for making room air to pass the evaporator so that cold air is discharged to the room again.
The outdoor unit is provided with an outdoor case having inlets and an outlet for drawing/discharging outdoor air, a compressor in the outdoor case for compressing high temperature, high pressure gaseous refrigerant passed through the evaporator, a condenser for making heat exchange between the refrigerant passed through the compressor with outdoor air to condense the refrigerant into medium temperature, high pressure liquid refrigerant, expansion means, such as a capillary tube, or an electronic expansion valve for decompressing the refrigerant passed through the condenser into low temperature, low pressure gaseous refrigerant, and an axial outdoor fan and a motor on one side of the condenser for making the outdoor air to pass the condenser, wherein the motor is a single phase, or three phase induction motor having a stator mounted on an inside of a housing, and a shaft and a rotor in a central part of the stator for rotating the rotor by a rotating magnetic field formed as AC is applied to the stator.
In general, the outdoor case has the inlets in three sides for enhancing a fan efficiency, and the outlet in a top surface, for drawing air through the three sides, making the air to heat exchange, and discharging the air to the top surface.
The compressor, the condenser, the expansion means, and the evaporator are connected with the refrigerant pipelines to each other, for circulation of the refrigerant therethrough while the refrigerant is compressed, condensed, expanded, and evaporated.
In the meantime, the foregoing outdoor unit of the related art air conditioner has a limited installation place due to high concentration of a city, with consequential strengthening of environmental control, and becomes an object of complaints due to noise and heat emission. Particularly, for an apartment in a large group of apartment houses, installation of the air conditioner is regulated such that the outdoor unit is installed within a veranda due to outside appearance and noise.
Consequently, air conditioner outdoor units of a front suction/discharge type are employed in the large group of apartment houses recently, in which air is drawn only through a front, made to heat exchange, and discharged to the front, again.
However, the air conditioner outdoor units of a front suction/discharge type has low fan, and heat exchange efficiencies due to a smaller air suction area than the air conditioner outdoor unit of three side suction/discharge type.
Moreover, the general single phase or three phase induction motor used for the fan of the air conditioner outdoor unit of the front suction/discharge type has problems in that an overall efficiency is low below 40˜50%, and rotation speed variation is limited to a small range due to a narrow stable torque range. If a rotation speed is outside of the stable torque range, noise becomes heavier and efficiency becomes poorer.